Because only a moderate number of tags can be displayed, the computation of
tag clouds is a form of top-\(k\)  query: given any user-specified range of
cells, we seek the top-\(k\)  cells having the largest measures. There is a little
hope of answering such queries in near constant-time with respect to the number
of facts without an index or a buffer. Indeed, finding all
and only the elements with frequency exceeding a given frequency
threshold [1]} or merely finding the most frequent
element [2]} requires \(\Omega (m)\)  bits where \(m\)  is the number of
distinct items.
